Type-writing machine.



W. F. HELMOND. TYPE WRITING MACHINE. APPLICATION FILED JULY 17, 1911.

1,066,275. Patented July 1, 1913.

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WILLIAM F. I-IELlVIONID, OF HARTFORD, CONNECTICUT, ASSIGNOR TO UNDERWOODTYPEWRITER COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

TYPE-WRITING MACHINE.

Specification of Letters Patent.

Patented July 1, 1913.

Application filed July 17, 1911. 'Serial No. 638,806.

This invention relates to platen shifting mechanism of typewritingmachines, and especially to those of the Underwood frontstrike type ofmachine, in which the platen frame is mounted upon a letter-feedingcarriage, and is capable of shifting up and down upon said carriage.

As heretofore constructed, the platen frame has been connected to thecarriage by means of a linkage, so that the platen frame is given asubstantially vertical movement. Owing to the necessity of making theparts light, it has been found impracticable to make the platen frame ofgreat strength, and owing partly to the weakness of the platen frame,and partly to the liability of Wear of the shifting parts, it hasheretofore been found necessary to provide both front and rear stops atthe ends of the platen frame, upon which stops the platen frame settleswhen returned from capital to lower case posit-ion. In said machine, thetypes strike on the front of the platen, and the weight of the platenframe and its appurtenances is largely back of the platen. It has beenthe usual practice in constructing said machine, to provide a linkagecomprising rock arms which extend forwardly from a rock shaft mountedupon the carriage frame, said rock arms at their forward ends beingpivoted directly to the platen axle. A suitable guide link or linkscooperated with said rock arms to carry. the

platen frame up and down; but nevertheless owing to the aforementionedweakness and liability of wear, it is found important to have both frontand rear stops for the platen in its normal position. Considerabledifficulty'having been experienced in alining the types on thesemachines, particularly after they were somewhat worn, I have sought toovercome this difficulty by supporting the platen frame in a differentmanner. I have discovered that the platen frame when dropping to normalposition, does not always settle properly on its front stops, and I havefound that even a slight variation in the position of the platen at thefront thereof, would effect a serious disturbance of the alinement ofthe written characters. This was particularly true Where the machine hadbeen subjected to considerable use.

I have devised means for causing the platen frame to settle promptlyupon its front stops, regardless of the rear stops, and have thereforeovercome the aforementioned difl'iculty with the alinement of the types.In accomplishing this object, I have arranged gudgeons or hearings onthe platen frame at a point at or in rear of the center of gravity ofthe shifting mass, with the result that the platen frame, beingoverbalanced at its front portion, tends to sag down in front, and hencethe front stops are sure to strike the carriage; and since these stopsare practically in the same vertical plane as the writing line of theplaten, the alineme-nt is substantially improved, even though the platenframe does not settle fully on its rear stops, which may, in some cases,be omitted. The ditficulty is noticeable in wide carriage machineshaving very long platens and having proportionally weaker platen frames.I have found, upon applying the invention to such wide carriagemachines, that the lifliculty of alinement has been practically avoided.

Other objects and advantages will hereinafter appear.

In the accompanying drawings, Figure 1 is a fragmentary side view inelevation, partly broken away, to show the underlying structure. Fig. 2is a fragmentary view, in elevation, taken from the opposite directionto that of Fig. 1. Fig. 3 is a fragmentary top plan view, partly brokenaway to show the underlying structure. l

The letter-feeding carriage 1 is mounted upon a typewriter frame 102. Aframe 2, shiftably mounted on said carriage, carries a platen 3, thelatter having an axle 4t journaled in the platen frame ends. At one endthe platen axle 4: may revolve in a bushing 5 which may be used toprevent the endwise shake of the platen; said bushing having at one sidea rabbet or slot 6 in which engages a fixed guide? fastened by a screw 8to an end of the platen frame. The guide 7 may hear at one end againstthe hub 10 of the usual line-space wheel, and at the other end againstthe end 9 of slot 6. The hub 10 is fixed upon the axle 4 and the bushing5 is between the hub and the wall 2 forming one of the platen frameends; and the hub r of the plat-en is also fixed to the axle and bearsagainst the other side of said wall 2.

Owing to the use of separate gudgeons for supporting the platen. frame,an opportunity is given for using a bushing 5 of suflicient diameter topermit a deep slot 9 to be cut therein, so that ample bearing is securedfor the guide 7, and the liability of wear is reduced. The opposite endof the platen frame is indicated at 2, Fig. 3. The

guide 7, which is fixed on the carriage, per

mits the platen .to shift up and down, but not to move endwise.

The platen frame is connected to the carriage 1 by a pair of rock arms14, secured by means of pins 13 upon a horizontal rock shaft 11 mountedin bearings 12 on the carriage; said arms having open bearings 15 inwhich rest gudgeons l6 projecting from the platen frame ends. Thesegudgeons are preferably just a little back of the center of gravity ofthe mass of the shifting mass, including the platen frame, the platen,paper shelf 36, pressure rolls, paper guides, etc.; and: are arrangedbetween the platen axle and the rock shaft 11. In consequence of thisplacing of the gudgeons 16, it follows that when the platen frame isdropping to the Fig. 1 position after having been shifted up, the frontpart of the platen frame will tend to sag, particularly when the pivotsof the guide links 17 are a little worn; and hence it is insured thatwhen the platen frame comes to rest, the front stops 30 thereof willstrike the carriage, even if the rear of the carriage does not settleproperly; and hence the alinement will not be faulty, even though therear part of the platen frame remains a trifle elevated above its truenormal position, since the front stops 30 are about in the same verticalline as the printing line on the platen, which is usually on the samehorizontal plane as the axle 4. Said links 17, of which there is usuallyone at each end of the platen frame, are pivoted at 18 to the platenframe end, and at 19 to the carriage.

There is illustrated the usual spring 20 and spring-adjusting clutch 21,22. There is also shown the usual shift key lever 23 bearing upon a bellcrank 2% provided with a lifting rail 25, upon which runs a roller 26 ofthe platen frame, and whereby the platen frame is lifted. There is alsoshown. the usual counter balancing spring 27 connected to a bracket 28and a rack 29;

The platen frames front stops are designated as 30 and are provided oneat each end of the platen frame. The platen frame in the Underwoodmachine has usually been provided also with rear stops toengage some:

part of, the carriage. For the sake of illustratio-n, it will be notedthat the bar 31 extending along the back of the platen frame mayconstitute the rear stops, and may rest upon the hub portion of thebearings 1 as at Fig. l; but it will be noted that my invention rendersthese rear stops of comparatively little importance, and in fact in theprocess of manufacturing the Underwood machine, the platen frame may beso constructed that the rear stops do not quite touch, while the platenframe rests solely upon the front stops 30. The platen frame is liftedby the-rail 25, and if, at the subsequent dropping of said rail, theplaten frame should not drop upon its guide links ineXactly the mannerintended, it will nevertheless be the case that the front stops 30 willreach the carriage, thus insuring the correct alinement of the types,even though the rear portion of the platen frame may remain a littletilted upwardly.

The upward motion of the platen frame may be limited by shoulders 35striking stops 34L adjustably secured upon the ends of the carriage bymeans of screws 33 which pass through slotted portions 32 of the stops.

If there is any lost motion whatsoever, it will be shown in the erraticmovement of the rear of the platen frame 2, rather than the front of thesame. In view of this fact the front of the platen cylinder 3 will always move the same distance between the stops, so that there will be anaccurate alinement of the characters when impressed on the sheet ofpaper on the platen cylinder, and this will not be disturbed even by thestriking of the type bar itself.

When the platen shift rail is allowed to fall, the platen frame willdrop down with its front hanging a trifle lower than the back, since thecenter of gravity isin front of the lugs 16, and since there will be alittle play in the pivotal supports of the arms 14 and 17. In sodropping, it will bring its stops 30 against the main carriage, andsince said stops are fairly close to the printing line on the platen,the type will strike the platen ust about where the printing line oughtto be, even if the stops 31 at the rear of the carriage have not comedown to their normal positions This is true particularly in typewritingmachines having long carriages. Where there is relatively great lengthand weight of the platen, the center of gravity may be even fartherforward than it is in machines having the ordinary short carriage. Itresults from this that the supplementary carriage or platen framenormally rests on the stops 30, and, owing to the fact that said stopsare near the printing line, irregularities of other adjustments of theplaten frame will be relatively unimportant.

return movement of said platen frame, and

counter-balancing mechanism normally tending to lift said platen frame,connected to the latter at a point slightly to the rear of the center ofgravity of said platen frame and behind the axis of said platen.

2. The combination with a carriage, of a platen frame movable relativelytosaidcarriage, a hub on said platen frame having a rabbet therein, anda guide on said carriage depending into said rabbet and engaging theside thereof, to prevent endwise movement of the platen frame and topermit vertical movement of said platen. frame.

3. The combination with acarriage, of a liftable platen frame thereon, aplaten on said frame, two pivoted guide-supports for said platen frame,said supports engaging the platen frame behind its center of gravity,cooperating guides for said platen frame, and stops at the front of saidplaten frame whereby it is normally supported; said platen being mountedso that its front or impression-receiving surface is adjacent to saidstops.

, 4. The combination with a main carriage, of a platen frame thereon andliftable relatively thereto, a platen on said platen frame and journaledbetween the front and the rear thereof, rock-arms pivotally connectingsaid carriage to said platen frame, said arms pivoted to said platenframe at a point behind its centerof gravity, and stops on said maincarriage adjacent to the front of the platen.

5. In a typewriting machine, the combination with a traveling carriage,of a platen frame shiftable therein, a platen having an axle journaledin said platen frame, a bushing loose on said axle and arranged to bearagainst a wall on said platen frame, a col lar on the opposite side ofsaid wall fast on said shaft, a guide on the main carriage ar rangedtoengage said bushing to prevent endwise shake of the platen frame inone direction, and a hub fixed on said axle to engage said guide toprevent endwise shake in the opposite direction.

6. In a typewriting machine, the combination with a carriage, of aplaten frame shiftable thereon, a platen having an axle journ aled insaid platen frame, a collar fixed on said shaft and arranged to bearagainst a Wall on said platen frame, a hub on the opposite side of saidwall fast on said axle, a bushing fitting between said wall and saidsecond collar, the axle being loose in the bushing, and a guide fast onthe main carriage arranged to bear against a shoulder or rabbet of saidbushing and against said hub, to prevent endwise shake of the platenframe.

7. In a front-strike typewriting machine,

.the combination with a traveling carriage, of a platen frame shlftablethereon, .a

platen and a paper table on said platen frame, supports on said platenframe intermediate the axle of said platen and said paper table, andguiding links tending to raisesaid platen frame and extending from therear of said traveling carriage to said supports.

8. In a front-strike typewriting machine, the combination with atraveling carriage, of a platen frame shiftable thereon, a platen onsaid platen frame, supports on said platen frame in rear of the axle ofsaid platen, links supporting part of the weight of said platenextending from the rear of said traveling carriage to said supports, andcooperating guide for the platen frame.

9. The combination with a carriage and a platen frame, of a platenhaving an axle journaled in the platen frame, rock arms mounted upon thecarriage and connected to the platen frame in rear of the platen axle, aguide fixed upon the carriage, and means upon or surrounding the platenaxle to engage said guide to prevent endwise shake of the platen; theplaten frame and platen being shiftable up and down while the platen iscontrolled by said guide.

WILLIAM F. HELMOND.

Witnesses W. M. BYORKMAN, LYMAN D. BROUGHTON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

